Natural Fe-oxide and -oxyhydroxide nanoparticles: an EPR and SQUID investigation

Carbone, Cristina; Benedetto, Francesco Di; Marescotti, Pietro; Sangregorio, Claudio; Sorace, Lorenzo; Lima, Nicola; Romanelli, Marco; Lucchetti̇, Gabriella; Cipriani, Curzio

doi:10.1007/s00710-005-0098-0

Cited by 49 publications

(30 citation statements)

References 14 publications

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“…We note that the formation of radiating goethite needles on a central iron oxide aggregate has been described previously in two interesting and relevant publications [11,33]. In these examples, goethite needles were found to form on the surface of larger Fe 2 O 3 particles when suspensions of these particles contained sulfate ions.…”

Section: Discussionmentioning

confidence: 78%

An electron microscopy study of the crystal growth of schwertmannite needles through oriented aggregation of goethite nanocrystals

Hockridge¹,

Jones²,

Loan³

et al. 2009

Journal of Crystal Growth

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a b s t r a c tThe formation of the iron oxyhydroxide schwertmannite has been monitored by time-resolved transmission electron microscopy (TEM) studies. Schwertmannite aggregates are found to form initially as spherical agglomerates of ferrihydrite crystallites, which then begin to grow characteristic needles on their surfaces. High-resolution images of the needles show that they are initially comprised of aligned goethite nanocrystals, which subsequently coarsen to form crystallographically coherent needles of goethite. Thus, needle formation on schwertmannite aggregates can be considered as the first stage in the phase transformation from schwertmannite to goethite. The results of this study suggest that schwertmannite is not a distinct mineral phase, but may be a mixture of ferrihydrite and poorly crystalline goethite with a distinctive morphology directed by the presence of surface-adsorbed sulfate anions.Crown

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Section: Discussionmentioning

confidence: 78%

An electron microscopy study of the crystal growth of schwertmannite needles through oriented aggregation of goethite nanocrystals

Hockridge¹,

Jones²,

Loan³

et al. 2009

Journal of Crystal Growth

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“…However, an inverse trend was observed when cysteine was adsorbed on clays and on iron oxides Vieira et al 2011). The resonance line g=4.1 could be due to Fe 3+ with rhombic symmetry as well as the interaction of Fe 3+ with organic matter (Guskos et al 2002;Carbone et al 2005;Mota et al 2009). The intensities line g = 4.1 obtained for unmodified and modified montmorillonite were 2.73 and 3.27 respectively (Carneiro et al 2011), and after these clays were mixed with artificial seawater in two different pHs, the intensities showed a variation from 1.33 to 3.28 Carneiro et al 2011).…”

Section: Discussionmentioning

confidence: 93%

“…Table 3 shows intensity lines of EPR of the samples of nucleic acid bases adsorbed on clays in two different pHs (2.00, 7.00). The resonance line g≈2 is due to hydroxides and oxides of Fe 3+ (Guskos et al 2002;Carbone et al 2005;Mota et al 2009). The intensities M montmorillonite and MM modified montmorillonite.…”

Section: Discussionmentioning

confidence: 97%

Adsorption of Adenine, Cytosine, Thymine, and Uracil on Sulfide-Modified Montmorillonite: FT-IR, Mössbauer and EPR Spectroscopy and X-Ray Diffractometry Studies

Carneiro

Berndt

Souza

et al. 2011

Orig Life Evol Biosph

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In the present work the interactions of nucleic acid bases with and adsorption on clays were studied at two pHs (2.00, 7.00) using different techniques. As shown by Mössbauer and EPR spectroscopies and X-ray diffractometry, the most important finding of this work is that nucleic acid bases penetrate into the interlayer of the clays and oxidize Fe(2+) to Fe(3+), thus, this interaction cannot be regarded as a simple physical adsorption. For the two pHs the order of the adsorption of nucleic acid bases on the clays was: adenine ≈ cytosine > thymine > uracil. The adsorption of adenine and cytosine on clays increased with decreasing of the pH. For unaltered montmorillonite this result could be explained by electrostatic forces between adenine/cytosine positively charged and clay negatively charged. However for montmorillonite modified with Na(2)S, probably van der Waals forces also play an important role since both adenine/cytosine and clay were positively charged. FT-IR spectra showed that the interaction between nucleic acid bases and clays was through NH(+) or NH (2) (+) groups. X-ray diffractograms showed that nucleic acid bases adsorbed on clays were distributed into the interlayer surface, edge sites and external surface functional groups (aluminol, silanol) EPR spectra showed that the intensity of the line g ≈ 2 increased probably because the oxidation of Fe(2+) to Fe(3+) by nucleic acid bases and intensity of the line g = 4.1 increased due to the interaction of Fe(3+) with nucleic acid bases. Mössbauer spectra showed a large decreased on the Fe(2+) doublet area of the clays due to the reaction of nucleic acid bases with Fe(2+).

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“…This is certainly true for nanoparticle goethite and hematite, where bulk antiferromagnetic coupling is reduced and superparamagnetic activity is enhanced with reduced size (Carbone et al 2005). An excellent review of the subject by Rancourt (2001) is available.…”

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confidence: 99%

Structure, Chemistry, and Properties of Mineral Nanoparticles

Waychunas¹,

Zhang²

2008

Elements

108

103

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Nanoparticle properties can depart markedly from their bulk analog materials, including large differences in chemical reactivity, molecular and electronic structure, and mechanical behavior.The greatest changes are expected at the smallest sizes, e.g. 10 nm and below, where surface effects are expected to dominate bonding, shape and energy considerations. The precise chemistry at nanoparticle interfaces can have a profound effect on structure, phase transformations, strain, and reactivity. Certain phases may exist only as nanoparticles, requiring transformations in chemistry, stoichiometry and structure with evolution to larger sizes. In general, mineralogical nanoparticles have been little studied. WHAT'S REALLY DIFFERENT ABOUT NANOPARTICLESNanoparticles, particularly those with diameters of less than 10 nm, have a high proportion of atoms near their surfaces (ca. 16% for a 10 nm cube). Because of this, several important aspects of surfaces can drive deviations from bulk structure and chemistry at different size scales. Size also directly affects a number of other bulk properties due to restriction on wave function radius, separation of defects and interacting strain fields, the relative overall dominance of bulk or surface energy, and changes in vibrational properties. Studies of nanoparticles connect with several other important scientific areas dealing with lower

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Natural Fe-oxide and -oxyhydroxide nanoparticles: an EPR and SQUID investigation

Cited by 49 publications

References 14 publications

An electron microscopy study of the crystal growth of schwertmannite needles through oriented aggregation of goethite nanocrystals

An electron microscopy study of the crystal growth of schwertmannite needles through oriented aggregation of goethite nanocrystals

Adsorption of Adenine, Cytosine, Thymine, and Uracil on Sulfide-Modified Montmorillonite: FT-IR, Mössbauer and EPR Spectroscopy and X-Ray Diffractometry Studies

Structure, Chemistry, and Properties of Mineral Nanoparticles

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